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Raised beds let you grow a LOT in less space.

by David Wann
photos courtesy David Wann

Raised beds are a common sight in local yards, as more and more people discover the joys, savings and benefits of growing their own vegetables.

These local gardeners join millions worldwide who use raised beds, a technique practiced in Greece as early as 3,000 B.C. Raised beds are typically plots less than 4 feet wide with reachable access to plants from paths on either side. Beds can be any length, but are often 6 to 8 feet long, with frames of wood, stone or concrete.

buildup    Raised beds can deliver much higher yields per square foot than conventional growing techniques because the elevated soil warms up earlier in spring and drains better, reducing waterborne diseases and making more air available to the plants’ root zones.

By design, this structural and biological way of growing gives plants what they need: loose, rich soil with a high percentage of organic material that enables deep root penetration and good nutrition. Raised-bed soil remains loose and aerated, because it’s not compressed by being walked on.

Typically, raised beds have fewer weeds, which means you’ll spend less time maintaining them. Spacing plants close together in a raised bed crowds out weeds, and the reachable access makes it easier to weed, harvest and control insects. The framed walls of a raised bed double as a low bench to sit on while working, and the higher soil level grants easier access to those in wheelchairs and walkers. The frames also prevent soil erosion and provide a physical barrier from pests like rabbits and mice. Many growers build hoop houses made from plastic sheets or chicken wire over their raised beds for additional protection from hail, frost and critters.

Raised beds have psychological benefits, too: Besides the physical and mental profits of gardening, the finite beds aren’t overwhelming to maintain, so you have more time to pamper and fine-tune them.

    Here’s a brief guide to creating a raised bed in your yard:
Location, Location, Location

For best results, choose a location that gets at least six hours a day of direct sunlight. Try to pick a site that’s also visible throughout your landscape, because you’ll likely get nice growth that you’ll want to highlight.

Site the bed away from trees (whose roots will compete for water) and close to a water source. In hot summers, a drip-irrigation system with a timer will make your beds far more self-sufficient.

Before planting, many gardeners lay down cardboard-sheet mulch or plastic sheets to kill grass and weeds. Lay the mulch several weeks before digging the soil, then loosen the dirt and remove rocks and any hardpan soil to improve drainage.

Build, Build, Build

Wood, brick, stone, recycled plastic lumber and cement blocks are popular materials for framing raised beds. If using wood, choose naturally rot-resistant wood such as cedar, redwood or locust. Never use chemically treated wood, because it will inhibit plant growth.

If using concrete blocks, pour an 8-inch foundation beneath them to prevent heaving and cracking. Three layers of blocks (about 2 feet tall) is a good height that provides protection from rabbits and creates a place to set tools and beverages. Finish concrete blocks with stucco to moistureproof them.

Mulch paths around the beds with wood chips, burlap bags or crushed rock to keep down weeds.

Amend, Amend, Amend

Don’t scrimp with amendments, since good soil is what makes a raised bed successful. A mixture of garden soil, compost and topsoil will get your bed off to a good start.

The perfect garden soil resembles a moist sponge that won’t drip a lot of water when squeezed, yet holds water in the root zone where it’s needed. In other words, it drains but also absorbs water. If buying soil, pay a little extra for a product with high-quality organic content and a high percentage of essential nutrients like nitrogen, phosphorus and potassium.

To figure out how much soil you’ll need, multiply your bed’s height by width by depth and purchase amendments by the cubic yard. You can tailor the soil in your beds to meet the needs of the crops growing there. For example, potatoes and tomatoes prefer slightly acidic soil, so the addition of elemental sulfur will yield better results. Root crops like carrots, beets and potatoes thrive with generous supplements of rock phosphate or bonemeal.

Plant, Plant, Plant

Now comes the fun part: planting and nurturing your favorite vegetables toward harvest. Plant greens closer to the bed’s path sides, and place longer-season crops in the center. Pay attention to the sun’s angle though. Taller crops like tomatoes and corn should be planted on the bed’s northern end to avoid shading shorter crops. Crops with deep roots, like carrots, should be planted next to shallow-rooted crops like lettuce, and both would benefit from the nitrogen supplied by beans.

Place plants close together in a triangular or staggered pattern throughout the bed so their leaves will overlap slightly at maturity. This allows for more plants per square foot and produces a continuous leafy canopy that shades the bed, moderates soil temperature, conserves moisture and discourages weeds. To maintain a rich soil, add 2 inches of compost to the surface of the raised bed at the beginning of each crop cycle.

Intense, Intense, Intense

John Jeavons, a guru of the biointensive growing technique and author of How to Grow More Vegetables, Fruits, Nuts, Berries, Grains, and Other Crops Than You Ever Thought Possible On Less Land Than You Can Imagine, prefers raised beds because they boost yields.

“I’ve always been curious about just how small an area could provide enough food for one individual,” Jeavons says. In Boulder County’s short, four-month growing season, Jeavons believes 200 square feet of raised-bed gardens could provide all the vegetables the typical American consumes, with as little as 30 minutes of labor a day.

So start planning your raised beds now for big yields this summer!

    David Wann has gardened for 30 years in various zones in Colorado and has written 10 books, including Affluenza, The Zen of Gardening and The New Normal. He currently coordinates a neighborhood garden in Golden.